Seven speed dual clutch transmission with four axes of rotation

ABSTRACT

A transmission is connectable to an input member and includes an output gear, first and second shaft members, first and second countershaft members, a reverse shaft, a plurality of co-planar gear sets, and a plurality of torque transmitting devices. The torque transmitting devices include a plurality of synchronizer assemblies and a dual clutch assembly. The transmission is operable to provide at least one reverse speed ratio and a plurality of forward speed ratios between the input member and the output member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.61/218,247, filed on Jun. 18, 2009, which is hereby incorporated in itsentirety herein by reference.

TECHNICAL FIELD

The present disclosure relates to transmissions and more particularly toa compact, dual clutch multiple speed transmission having four axes toestablish seven or more gear speeds.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission having countershafts and co-planargear sets uses countershaft gears with a different, dedicated gear pairor set to achieve each forward speed ratio. Accordingly, the totalnumber of gears required in this typical design is two times the numberof forward speeds, plus three for reverse. This necessitates a largenumber of required gear pairs, especially in transmissions that have arelatively large number of forward speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needin the art for a transmission having improved packaging while providingdesirable gear ratios and torque ranges.

SUMMARY

The present invention provides a transmission having an input member, anoutput member, first and second shaft members, first and secondcountershaft members, a reverse, shaft, a plurality of co-planar gearsets, and a plurality of torque transmitting devices. The torquetransmitting devices include a plurality of synchronizer assemblies anda dual clutch assembly. The transmission is operable to provide at leastone reverse speed ratio and a plurality of forward speed ratios betweenthe input member and the output member.

In one aspect of the present invention, the transmission includes atransmission housing and a dual clutch assembly having a first andsecond clutch and a clutch housing. The clutch housing is connectable toa flywheel of an engine. The clutch housing is rotationally supportedwithin the transmission housing.

In another aspect of the present invention, the transmission includes afirst, second, third, fourth and fifth gear sets. The first gear setincludes a first gear in mesh with a second gear and a reverse gear inmesh with the second gear, the second gear set includes a first gear inmesh with a second gear and a third gear, the third gear set includes afirst gear in mesh with a second gear and a third gear, the fourth gearset includes a first gear in mesh with a second gear and the fifth gearset includes a first gear in mesh with a second gear.

In another aspect of the present invention, a first transmission inputmember is rotatably supported in the transmission housing. Each of thefirst gears of the third, fourth and fifth gear sets are rotatably fixedfor common rotation with the first transmission input member.

In another aspect of the present invention, a second transmission inputmember is rotatably supported in the transmission housing. Each of thefirst gears of the first and second gear sets are rotatably fixed forcommon rotation with the second transmission input member. The secondtransmission input member is concentric with the first transmissioninput member and at least partially surrounds the first transmissioninput member.

In another aspect of the present invention, a first synchronizerassembly selectively connects the second gear of the second gear set tothe second countershaft.

In another aspect of the present invention, a second synchronizerassembly selectively connects at least one of the second gear of thefirst gear set and the third gear of the second gear set to the firstcountershaft.

In another aspect of the present invention, a third synchronizerassembly selectively connects at least one of the second gear of thethird gear set and the second gear of the fifth gear set to the secondcountershaft.

In another aspect of the present invention, a fourth synchronizerassembly selectively connects at least one of the third gear of thethird gear set and the second gear of the fourth gear set to the firstcountershaft.

In another aspect of the present invention, a fifth synchronizerassembly selectively connects the reverse gear to the reverse shaft.

In another aspect of the present invention, a first countershafttransfer gear is fixed to the first countershaft for common rotationwith the first countershaft, a second countershaft transfer gear isfixed to the second countershaft for common rotation with the secondcountershaft and a reverse shaft transfer gear is fixed to the reverseshaft for common rotation with the first reverse shaft. The first andsecond countershaft transfer gears and the reverse shaft transfer geartransfer torque from at least one of the first and second countershaftsand reverse shaft to an output member.

In another aspect of the present invention, the selective engagement ofdual clutch assembly interconnects the dual clutch housing with at leastone of the first and the second transmission input members and theselective engagement of at least one of the synchronizer assembliesestablishes at least one of seven forward speed ratios between the atleast one of the first and the second transmission input members and theoutput member.

In another aspect of the present invention, two of the five co-planargear sets are configured to produce two gear ratios each and two otherof the five co-planar gear sets are configured to produce one gear ratioeach.

In another aspect of the present invention, one of the five co-planargear sets is configured to produce one forward gear ratio one reversegear ratio.

In another aspect of the present invention, one of the five co-planargear sets is configured to produce a reverse gear ratio using a reversegear selectively connectable to a reverse shaft, wherein the reverseshaft is a separate shaft that is parallel with and spaced apart fromthe countershafts.

In another aspect of the present invention, one of the five co-planargear sets includes a reverse gear and a park gear rotatable supported ona reverse shaft that is a fourth axis of rotation.

In yet another aspect of the present invention, the five synchronizerassemblies include three two-way synchronizers.

In yet another aspect of the present invention, the five synchronizerassemblies include two one-way synchronizers.

In yet another aspect of the present invention, the transmission isoperable to provide at least seven forward speed ratios.

The above features and advantages and other features and advantages ofthe present invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic view of an embodiment of a seven speedtransmission, in accordance with the present invention.

DESCRIPTION

Referring to FIG. 1, a multiple speed transmission is generallyindicated by reference number 10. The transmission 10 is connectable toan input member 12 and includes an output member or gear 14. In thepresent embodiment, the input member 12 is a shaft and the output member14 is a gear, however those skilled in the art will appreciate that theinput member 12 may be components other than shafts and the outputmember 14 may be a component, such as a shaft, other than a gear.

The input member 12 is continuously connected with an engine or engineflywheel (not shown) or other torque producing machine to provide adriving torque to input member 12. The output member or gear 14rotatably drives a final drive or differential assembly 16. The assembly16 transfers torque delivered by output member 14, ultimately, to a pairroad wheels (not shown).

The transmission 10 includes a housing 18 that at least partiallyencloses a gearing arrangement 20. The gearing arrangement 20 includesvarious shafts or members, co-planar intermeshing gear sets, a dualclutch assembly, and selectively engageable synchronizers, as will bedescribed herein. For example, the gearing arrangement 20 includes afirst transmission input shaft or member 22, a second transmission inputshaft or member 24, a first countershaft 26, a second countershaft 28and a reverse shaft 30. The second transmission input shaft or member 24is a sleeve (hollow) shaft that is concentric with and overlies thefirst transmission input shaft or member 22. The first countershaft 26,the second countershaft 28 and the reverse shaft 30 are each spacedapart from and parallel with the first and second transmission inputshaft members 22, 24. The first and second transmission input shafts 22,24 define a first axis of rotation, the first countershaft 26 defines asecond axis of rotation, the second countershaft 28 defines a third axisof rotation and the reverse shaft 30 defines a fourth axis of rotation.

A dual clutch assembly 32 is connectable between the input member 12 andthe first and second transmission input shaft members 22, 24. The dualclutch assembly 32 includes a clutch housing 34 connectable for commonrotation with the input member 12. Further, the dual clutch assembly 32has first and second clutch elements or hubs 36 and 38. Clutch elements36 and 38 together with the clutch housing 34 are configured to form afriction clutch, as is known in the art as a dual clutch. Morespecifically, clutch elements 36, 38 and the clutch housing 34 havefriction plates mounted thereon or otherwise coupled thereto thatinteract to form a friction clutch. The clutch element 36 is connectedfor common rotation with the first transmission input shaft or member 22and the clutch element 38 is connected for common rotation with thesecond transmission input shaft or member 24. Thus, selective engagementof clutch element 36 with the clutch housing 34 connects the inputmember 12 for common rotation with the first transmission input shaftmember 22. Selective engagement of clutch element 38 with the clutchhousing 34 connects the input member 12 for common rotation with thesecond transmission input shaft member 24.

The gearing arrangement 20 also includes a plurality of co-planar,meshing gear sets 40, 50, 60, 70 and 80. The present inventioncontemplates that the plurality of co-planar, meshing gear sets 40, 50,60, 70 and 80 may be arranged axially along transmission input shafts22, 24 in an order other than that which is shown in FIG. 1 and still bewithin the scope of the invention. Co-planar gear set 40 includes gear42, gear 44 and a reverse gear 46. Gear 42 is rotatably fixed andconnected for common rotation with the second transmission input shaftmember 24. Gear 44 is selectively connectable for common rotation withthe first countershaft member 26 and meshes with gear 42. Reverse gear46 meshes with gear 44 and is selectively connectable for commonrotation with reverse shaft 30. It should be appreciated that gear 42may be a separate gear structure fixed to the second transmission inputshaft member 24 or gear teeth/splines formed on an outer surface of thesecond transmission input shaft member 24 without departing from thescope of the present invention. Gear set 40 is disposed proximate a wall48 of the transmission housing 18 that is on a front or side of thetransmission 10 proximate the dual clutch assembly 32.

Co-planar gear set 50 includes gear 52, gear 54 and gear 56. Gear 52 isrotatably fixed and connected for common rotation with the secondtransmission input shaft member 24 and meshes with gear 54 and gear 56.Gear 54 is selectively connectable for common rotation with the secondcountershaft member 28. Gear 56 is selectively connectable for commonrotation with the first countershaft member 26. Gear set 50 ispositioned adjacent gear set 40.

Co-planar gear set 60 includes gear 62, gear 64 and gear 66. Gear 62 isrotatably fixed and connected for common rotation with the firsttransmission input shaft member 22 and meshes with gear 64 and gear 66.Gear 64 is selectively connectable for common rotation with the secondcountershaft member 28. Gear 66 is selectively connectable for commonrotation with the first countershaft member 26. Gear set 60 is disposedadjacent gear set 50.

Co-planar gear set 70 includes gear 72 and gear 74. Gear 72 is rotatablyfixed and connected for common rotation with the first transmissioninput shaft member 22 and meshes with gear 74. Gear 74 is selectivelyconnectable for common rotation with the first countershaft member 26.Gear set 70 is positioned adjacent gear set 60.

Co-planar gear set 80 includes gear 82 and gear 84. Gear 82 is rotatablyfixed and connected for common rotation with the first transmissioninput shaft member 22 and meshes with gear 84. Gear 84 is selectivelyconnectable for common rotation with the second countershaft member 28.Gear set 80 is positioned between gear set 70 and an end wall 88 of thetransmission housing 18.

Further, a first countershaft transfer gear 100 is rotatably fixed andconnected for common rotation with the first countershaft member 26. Asecond countershaft transfer gear 110 is rotatably fixed and connectedfor common rotation with the second countershaft member 28. A reverseshaft transfer gear 111 is rotatably fixed and connected for commonrotation with the reverse shaft 30. First countershaft transfer gear100, second countershaft transfer gear 110 and reverse shaft transfergear 111 are each configured to mesh with output member 14. However,first countershaft transfer gear 100, second countershaft transfer gear110 and reverse shaft transfer gear 111 do not mesh with each other. Thefirst countershaft transfer gear 100 is disposed between gear 44 and endwall 48 of the transmission housing 18. The second countershaft transfergear 110 is disposed between gear 54 and end wall 48 of the transmissionhousing 18. The reverse shaft transfer gear 111 is disposed between thereverse gear 46 and end wall 48 of the transmission housing 18. Theoutput member 14 is co-planar with first and second countershafttransfer gears 100, 110 and reverse shaft transfer gear 111.

A park gear 112 is provided for placing transmission 10 in a park modethat prevents output member 14 from rotating. Park gear 112 is rotatablyfixed and connected for common rotation with the reverse shaft 30. Whenthe park mode is activated park gear 112 is rotatably fixed preventingreverse shaft 30 and transfer gear 111 from rotating, which thusprevents output gear 14 from rotating. Alternatively, the presentinvention contemplates fixedly disposing park gear 112 on the first orsecond countershafts 26, 28 to achieve the park mode function. Moreover,the axial location of park gear 112 along reverse shaft 30 may bechanged in accordance with available packaging space.

The transmission 10 further includes a plurality of selectivelyengageable synchronizer assemblies 150, 152, 154, 156 and 158.Synchronizers 152, 154 and 156 are double sided synchronizers andgenerally include a shift fork (not shown) that is bi-directionallytranslated by an actuator (not shown) into at least two engagedpositions and a neutral or disengaged position. In the presentembodiment, synchronizer 152 is selectively actuatable to connect gear44 for common rotation with the first countershaft member 26 andsynchronizer 152 is selectively actuatable to connect gear 56 for commonrotation with the first countershaft member 26. Synchronizer 154 isselectively actuatable to connect for common rotation gear 64 with thesecond countershaft 28 and is selectively actuatable to connect forcommon rotation gear 84 with the second countershaft 28. Synchronizer156 is selectively actuatable to connect for common rotation gear 66with the first countershaft member 26 and is selectively actuatable toconnect for common rotation gear 74 with the first countershaft member26.

Synchronizers 150 and 158 are single sided synchronizers that generallyinclude a shift fork (not shown) that is bi-directionally translated byan actuator (not shown) into either an engaged position or a neutral ordisengaged position. In the present embodiment, synchronizer 150 isselectively actuatable to connect for common rotation gear 54 with thesecond countershaft 28. Synchronizer 158 is selectively actuatable toconnect reverse gear 46 for common rotation with the reverse shaft 30.

The transmission 10 is capable of transmitting torque from the inputshaft 12 to the output gear member 14 in at least seven forward torqueratios and at least one reverse torque ratio. Each of the forward torqueratios and the reverse torque ratio is attained by selective engagementof the dual clutch assembly 32 and one or more of the synchronizerassemblies 150, 152, 154, 156 and 158. Those skilled in the art willreadily understand that a different speed ratio is associated with eachtorque ratio.

It should be appreciated that each individual gear set 40, 50, 60, 70and 80 and reverse gear 90 provides one or more forward and/or reversegear ratios upon selective engagement of the synchronizer assemblies150, 152, 154, 156 and 158. It should also be appreciated that aparticular forward or reverse speed ratio may be achieved by differentcombinations of synchronizer and associated gear sets or gears withoutdeparting from the scope of the present invention.

For example, to establish the reverse torque ratio, clutch element 38 isengaged and synchronizer 158 is activated. Clutch element 38 couples theinput member 12 with the second transmission input shaft member 24.Synchronizer 158 connects reverse gear 46 to the reverse shaft 30. Morespecifically, input torque from the input shaft 12 is transferredthrough the dual clutch assembly 32 to the second transmission inputshaft member 24, through gear 42 to gear 44, through gear 44 to reversegear 46, from reverse gear 46 to the reverse shaft 30 throughsynchronizer 158 to reverse transfer gear 111 and from reverse transfergear 111 to the output member 14.

To establish a first forward torque ratio (i.e. a 1st gear), clutchelement 36 is engaged and synchronizer 156 is activated. Clutch element36 couples the input member 12 with the first transmission input shaftmember 22. Synchronizer 156 couples gear 74 to the first countershaftmember 26. Input torque from the input member 12 is transferred throughthe dual clutch assembly 32 to the first transmission input shaft member22 to gear 72. Gear 72 transfers torque to gear 74 which transfers thetorque to the first countershaft member 26 through synchronizer 156 andto first countershaft transfer gear 100 and then from first countershafttransfer gear 100 to the output member 14.

To establish a second forward torque ratio (i.e. a 2nd gear), clutchelement 38 is engaged and synchronizer 152 is activated. Clutch element38 couples the input member 12 to the second transmission input shaftmember 24 which rotates gear 42. Synchronizer 152 couples gear 44 to thefirst countershaft member 26. Accordingly, input torque from the inputmember 12 is transferred through the dual clutch assembly 32 to thesecond transmission input shaft member 24, through gear 42 to gear 44,from gear 44 to synchronizer 152, from synchronizer 152 to the firstcountershaft member 26 and from the first countershaft member 26 to thefirst countershaft transfer gear 100 and the output member 14.

To establish a third forward torque ratio (i.e. a 3rd gear), clutchelement 36 is engaged and synchronizer 156 is activated. Clutch element36 couples the input member 12 to the first transmission input shaftmember 22 which rotates gear 62. Synchronizer 156 couples gear 66 to thefirst countershaft member 26. Thus, input torque from the input member12 is transferred through the dual clutch assembly 32 to the firsttransmission input shaft member 22, through gear 62 to gear 66, throughgear 66 to synchronizer 156, from synchronizer 156 to the firstcountershaft member 26, from the first countershaft member 26 to thefirst countershaft transfer gear 100 and then from first countershafttransfer gear 100 to the output member 14.

To establish a fourth forward torque ratio (i.e. a 4th gear), clutchelement 38 is engaged and synchronizer 152 is activated. Clutch element38 couples the input member 12 to the second transmission input shaftmember 24 which rotates gear 52. Synchronizer 152 couples gear 56 to thefirst countershaft member 26. Thus, input torque from the input member12 is transferred through the dual clutch assembly 32 to the secondtransmission input shaft member 24 to gear 52, then from gear 52 to gear56, from gear 54 to synchronizer 152, from synchronizer 152 to the firstcountershaft member 26, from the first countershaft member 26 to firstcountershaft transfer gear 100 and then from first countershaft transfergear 100 to the output member 14.

To establish a fifth forward torque ratio (i.e. a 5th gear), clutchelement 36 is engaged and synchronizer 154 is activated. Clutch element36 couples the input member 12 to the first transmission input shaftmember 22 which rotates gear 62. Synchronizer 154 couples gear 64 to thesecond countershaft member 28. Input torque from the input member 12 istransferred through the dual clutch assembly 32 to the firsttransmission input shaft member 22, from first transmission input shaftmember 22 to gear 62, from gear 62 to gear 64, from gear 64 to thesecond countershaft member 28 through synchronizer 154, to secondcountershaft transfer gear 110 and from second countershaft transfergear 110 to the output member 14.

To establish a sixth forward torque ratio (i.e. a 6th gear), clutchelement 38 is engaged and synchronizer 150 is activated. Clutch element38 couples the input member 12 to the second transmission input shaftmember 24 which rotates gear 52. Synchronizer 150 couples gear 54 to thesecond countershaft member 28. Thus, input torque from the input member12 is transferred through the dual clutch assembly 32 to the secondtransmission input shaft member 24 to gear 52, then from gear 52 to gear54, from gear 54 to synchronizer 150, from synchronizer 150 to thesecond countershaft member 28, from the second countershaft member 28 tosecond countershaft transfer gear 110 and then from second countershafttransfer gear 110 to the output member 14.

To establish a seventh forward torque ratio (i.e. a 7th gear), clutchelement 36 is engaged and synchronizer 154 is activated. Clutch element36 couples the input member 12 to the first transmission input shaftmember 22 which rotates gear 82. Synchronizer 154 couples gear 84 to thesecond countershaft member 28. Input torque from the input member 12 istransferred through the dual clutch assembly 32 to the firsttransmission input shaft member 22, from first transmission input shaftmember 22 to gear 82, from gear 82 to gear 84, from gear 84 to thesecond countershaft member 28 through synchronizer 154, to secondcountershaft transfer gear 110 and from first countershaft transfer gear110 to the output member 14.

Again, it should be appreciated that any one of the gear sets of gearsets 40, 50, 60, 70 and 80 and reverse gear 46 may be changed to producea certain forward and reverse torque ratio without departing from thescope of the present invention.

The present invention contemplates that a variety of torque ratios(i.e., the ratio of torque of the output member 14 to the input member12) and ratio steps are achievable through the selection of tooth countsof the gears of the transmission 10. The present invention has manyadvantages and benefits over the prior art. For example, each of thedouble synchronizer assemblies 152, 154, 156 is driven by one fork andone rail assembly. Moreover, each of the single synchronizer assemblies150, 158 is driven by two forks on the same rail assembly. Hence, thereare four rails to drive all five synchronizers. Furthermore,countershafts 26, 28 can switch positions. Thus, a transmission having amore simplified actuation and control system, reduced mass and cost andimproved packaging is achieved.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

1. A transmission comprising: a transmission housing; a dual clutchassembly having a clutch housing connectable to an engine output member,wherein the clutch housing is rotationally supported within thetransmission housing; a first, second, third, fourth and fifth gear set,wherein the first gear set includes a first gear in mesh with a secondgear and a reverse gear in mesh with the second gear, the second gearset includes a first gear in mesh with a second gear and a third gear,the third gear set includes a first gear in mesh with a second gear anda third gear, the fourth gear set includes a first gear in mesh with asecond gear, the fifth gear set includes a first gear in mesh with asecond gear; a first transmission input member rotatably supported inthe transmission housing, and wherein each of the first gears of thethird, fourth and fifth gear sets are rotatably fixed for commonrotation with the first transmission input member; a second transmissioninput member rotatably supported in the transmission housing, whereineach of the first gears of the first and second gear sets are rotatablyfixed for common rotation with the second transmission input member andwherein the second transmission input member is concentric with thefirst transmission input member and at least partially surrounds thefirst transmission input member; a first countershaft rotatablysupported within the transmission housing and spaced apart from andparallel with the first and second transmission input members, whereinthe second gear of the first gear set, the third gear of the second gearset, the third gear of the third gear set and the second gear of thefourth gear set are each selectively connectable for common rotationwith the first countershaft; a second countershaft rotatably supportedwithin the transmission housing and spaced apart from and parallel withthe first and second transmission input members, wherein the second gearof the second gear set, the second gear of the third gear set and thesecond gear of the fifth gear set are each selectively connectable forcommon rotation with the second countershaft; a reverse shaft rotatablysupported in the transmission housing and spaced apart from and parallelwith the first and second transmission input members for rotatablysupporting the reverse gear, wherein the reverse gear is selectivelyconnectable for common rotation with the reverse shaft; fivesynchronizer assemblies for selectively coupling at least one of thegears of the first, second, third, fourth and fifth gear sets with atleast one of the first countershaft, the second countershaft and reverseshaft, and wherein the selective engagement of dual clutch assemblyinterconnects the dual clutch housing with at least one of the first andthe second transmission input members and the selective engagement of atleast one of the five synchronizer assemblies establishes at least oneof seven forward speed ratios.
 2. The transmission of claim 1 wherein afirst of the five synchronizer assemblies selectively connects thesecond gear of the second gear set to the second countershaft.
 3. Thetransmission of claim 2 wherein a second of the five synchronizerassemblies selectively connects at least one of the second gear of thefirst gear set and the third gear of the second gear set to the firstcountershaft.
 4. The transmission of claim 3 wherein a third of the fivesynchronizer assemblies selectively connects at least one of the secondgear of the third gear set and the second gear of the fifth gear set tothe second countershaft.
 5. The transmission of claim 4 wherein a fourthof the five synchronizer assemblies selectively connects at least one ofthe third gear of the third gear set and the second gear of the fourthgear set to the first countershaft.
 6. The transmission of claim 5wherein a fifth of the five synchronizer assemblies selectively connectsthe reverse gear to the reverse shaft.
 7. The transmission of claim 1wherein the first gear set is adjacent the dual clutch assembly, thesecond gear set is adjacent the first gear set, the third gear set isadjacent the second gear set, the fourth gear set is adjacent the thirdgear set, and the fifth gear set is adjacent the fourth gear set.
 8. Thetransmission of claim 1 wherein the dual clutch assembly includes afirst clutch and a second clutch, wherein the second clutch isconfigured to selectively connect the clutch housing to the secondtransmission input member and wherein the five synchronizer assembliesincludes a first synchronizer assembly for selectively connecting thesecond gear of the second gear set to the second countershaft toestablish a sixth gear ratio.
 9. The transmission of claim 8 wherein thedual clutch assembly includes a first clutch and a second clutch,wherein the second clutch is configured to selectively connect theclutch housing to the second transmission input member and wherein thefive synchronizer assemblies includes a second synchronizer assembly forselectively connecting the second gear of the first gear set to thefirst countershaft to establish a second gear ratio.
 10. Thetransmission of claim 8 wherein the dual clutch assembly includes afirst clutch and a second clutch, wherein the second clutch isconfigured to selectively connect the clutch housing to the secondtransmission input member and wherein the five synchronizer assembliesincludes a second synchronizer assembly for selectively connecting thethird gear of the second gear set to the first countershaft to establisha fourth gear ratio.
 11. The transmission of claim 8 wherein the dualclutch assembly includes a first clutch and a second clutch, wherein thefirst clutch is configured to selectively connect the clutch housing tothe first transmission input member and wherein the five synchronizerassemblies includes a third synchronizer assembly for selectivelyconnecting the second gear of the third gear set to the secondcountershaft to establish a fifth gear ratio.
 12. The transmission ofclaim 8 wherein the dual clutch assembly includes a first clutch and asecond clutch, wherein the first clutch is configured to selectivelyconnect the clutch housing to the first transmission input member andwherein the five synchronizer assemblies includes a third synchronizerassembly for selectively connecting the second gear of the fifth gearset to the second countershaft to establish a seventh gear ratio. 13.The transmission of claim 8 wherein the dual clutch assembly includes afirst clutch and a second clutch, wherein the first clutch is configuredto selectively connect the clutch housing to the first transmissioninput member and wherein the five synchronizer assemblies includes afourth synchronizer assembly for selectively connecting the third gearof the third gear set to the first countershaft to establish a thirdgear ratio.
 14. The transmission of claim 8 wherein the dual clutchassembly includes a first clutch and a second clutch, wherein the firstclutch is configured to selectively connect the clutch housing to thefirst transmission input member and wherein the five synchronizerassemblies includes a fourth synchronizer assembly for selectivelyconnecting the second gear of the fourth gear set to the firstcountershaft to establish a first gear ratio.
 15. The transmission ofclaim 8 wherein the dual clutch assembly includes a first clutch and asecond clutch, wherein the second clutch is configured to selectivelyconnect the clutch housing to the second transmission input member andwherein the five synchronizer assemblies includes a fifth synchronizerassembly for selectively connecting the reverse gear to the reverseshaft to establish a reverse gear ratio.
 16. The transmission of claim 1further comprising a first countershaft transfer gear fixed to the firstcountershaft for common rotation with the first countershaft, a secondcountershaft transfer gear fixed to the second countershaft for commonrotation with the second countershaft and a reverse shaft transfer gearfixed to the reverse shaft for common rotation with the first reverseshaft and wherein the first and second countershaft transfer gears andthe reverse shaft transfer gear transfer torque from at least one of thefirst and second countershafts and reverse shaft to an output member.17. The transmission of claim 16 wherein the output member is a gearthat meshes with the each of the first and second countershaft transfergears and the reverse shaft transfer gear.
 18. The transmission of claim16 further comprising a park gear fixed to the reverse shaft, whereinthe park gear is configured to prevent rotation of the reverse shafttransfer gear and the output gear when the park gear is engaged.
 19. Atransmission comprising: a transmission housing; a dual clutch assemblyhaving a first and second clutch and a clutch housing, wherein theclutch housing is connectable to a flywheel of an engine and wherein theclutch housing is rotationally supported within the transmissionhousing; a first, second, third, fourth and fifth gear set, wherein thefirst gear set includes a first gear in mesh with a second gear and areverse gear in mesh with the second gear, the second gear set includesa first gear in mesh with a second gear and a third gear, the third gearset includes a first gear in mesh with a second gear and a third gear,the fourth gear set includes a first gear in mesh with a second gear,the fifth gear set includes a first gear in mesh with a second gear; afirst transmission input member rotatably supported in the transmissionhousing, and wherein each of the first gears of the third, fourth andfifth gear sets are rotatably fixed for common rotation with the firsttransmission input member; a second transmission input member rotatablysupported in the transmission housing, wherein each of the first gearsof the first and second gear sets are rotatably fixed for commonrotation with the second transmission input member and wherein thesecond transmission input member is concentric with the firsttransmission input member and at least partially surrounds the firsttransmission input member; a first synchronizer assembly selectivelyconnects the second gear of the second gear set to the secondcountershaft; a second synchronizer assembly selectively connects atleast one of the second gear of the first gear set and the third gear ofthe second gear set to the first countershaft; a third synchronizerassembly selectively connects at least one of the second gear of thethird gear set and the second gear of the fifth gear set to the secondcountershaft; a fourth synchronizer assembly selectively connects atleast one of the third gear of the third gear set and the second gear ofthe fourth gear set to the first countershaft; a fifth synchronizerassembly selectively connects the reverse gear to the reverse shaft; anda first countershaft transfer gear fixed to the first countershaft forcommon rotation with the first countershaft, a second countershafttransfer gear fixed to the second countershaft for common rotation withthe second countershaft and a reverse shaft transfer gear fixed to thereverse shaft for common rotation with the first reverse shaft andwherein the first and second countershaft transfer gears and the reverseshaft transfer gear transfer torque from at least one of the first andsecond countershafts and reverse shaft to an output member, and whereinthe selective engagement of dual clutch assembly interconnects the dualclutch housing with at least one of the first and the secondtransmission input members and the selective engagement of at least oneof the synchronizer assemblies establishes at least one of seven forwardspeed ratios between the at least one of the first and the secondtransmission input members and the output member.